A predictive model of the dynamics of body weight and food intake in rats submitted to caloric restrictions.

International audienceDynamics of body weight and food intake can be studied by temporally perturbing food availability. This perturbation can be obtained by modifying the amount of available food over time while keeping the overall food quantity constant. To describe food intake dynamics, we developed a mathematical model that describes body weight, fat mass, fat-free mass, energy expenditure and food intake dynamics in rats. In addition, the model considers regulation of food intake by leptin, ghrelin and glucose. We tested our model on rats experiencing temporally variable food availability. Our model is able to predict body weight and food intake variations by taking into account energy expenditure dynamics based on a memory of the previous food intake. This model allowed us to estimate this memory lag to approximately 8 days. It also explains how important variations in food availability during periods longer than these 8 days can induce body weight gains

Building Information Modelling (BIM) value realisation framework for asset owners

The paper is presenting a value realisation framework for asset owners based on an exploratory study. The study is descriptive in nature and adopting a qualitative approach towards data collection. The paper adopts the viewpoint of BIM business value measurement considering that; (i) if the process is better as a result of BIM-based processes, then it is different in some relevant way; (ii) if it is different in some relevant way as a result of certain BIM properties or characteristics, then the change is observable; (iii) if the change is observ-able because of certain direct BIM benefits, then it is countable; (iv) if it is countable using defined measurement metrics, then it is measurable; (v) if it is measurable using established measurement techniques, an organisation can value each unit and therefore, realise the benefits of BIM. The specific contribution of paper is to improve asset owners’ understanding of BIM-business value measurement techniques and approaches

Endovascular retrieval of two migrated venous stents by means of balloon catheters

AbstractThe usefulness of vascular stenting was demonstrated in both arterial and venous applications to restore patency and improve suboptimal results after percutaneous transluminal angioplasty. Dislodgment of venous stents with an embolization into the right cavities or the pulmonary artery, however, is one of the most feared complications of this procedure. Percutaneous removal of these migrated stents is an appealing method of replacing more invasive operative intervention with cardiopulmonary bypass, which may be very hazardous in these often severely ill patients. We describe the cases of two patients with stents that migrated into the right ventricle and the pulmonary artery. In one patient, we were able to successfully remove these stents by using an angioplasty balloon with an operative extraction from the iliac vein, thereby obviating the need for a major operative procedure. (J Vasc Surg 1998;28:541-6.

Les aspects parasitologiques de l'épidémiologie du paludisme dans le Sahara malien

Dans le cadre de l'évaluation épidémiologique de la Transsaharienne, une enquête transversale paludométrique a été réalisée d'Août 1988 à Septembre 1988 le long du tronçon malien. Neuf localités ont été visitées : Douentza, Gossi, Bourem, Almoustarat, Anefis, Aguel-Hoc, Tarlit, Tessalit, Kidal, Bouressa. 2185 unités ont été prélevées pour les études cliniques, parasitologiques et immunologiques. L'indice plasmodique global est de 5,3 % avec une grande variation du Sud (44,6 %) au Nord (0 %). L'indice gamétocytique et l'indice splénique sont très faibles. #P. falciparum est l'espèce dominante. #P. malariae a été décrit une fois en association avec #P. falciparum. #P. ovale n'a jamais été observé. Par contre un cas de #P. vivax a été décrit chez une jeune fille leucoderme de 8 ans à Kidal. #A. gambiae s.s. (forme Mopti) et #A. arabiensis sont les principaux vecteurs au Nord du Mali. Une hypothèse de circulation de #P. vivax dans le Sahara malien est émise. (Résumé d'auteur

Gamma rhythm communication between entorhinal cortex and dentate gyrus neuronal assemblies.

INTRODUCTION: Learning induces a dynamic reorganization of brain circuits but the neuronal mechanisms underlying this process are not well understood. Interregional gamma-frequency oscillations (~30 to 130 Hz) have been postulated as a mechanism to precisely coordinate upstream and downstream neuronal ensembles, for example, in the hippocampal system. The lateral (LEC) and medial (MEC) entorhinal cortex receive inputs from two distinct streams of cortical hierarchy (the “what” and the “where” paths) and convey these neuronal messages to the hippocampus. However, the mechanisms by which such messages are packaged and integrated or segregated by hippocampal circuits had yet to be explored. RATIONALE: Neuronal assemblies firing within gamma time frames in an upstream region can most effectively discharge their downstream partners. This gamma-time-scale organization appears essential for physiological functions because manipulations that impair precision timing of spikes in the hippocampus often affect behavior. However, direct support for distinct gamma-frequency communication in appropriate behavioral situations is missing. To bring physiological operations closer to behavior, we designed “spatial” and “object” learning tasks and examined the selective engagement of gamma-frequency communication between the MEC and LEC inputs and their target neuronal assemblies in the hippocampal dentate gyrus. We combined these correlational observations with optogenetic perturbation of gamma oscillations in LEC and MEC, respectively, to test their roles in pathway-specific neuronal communication and learning. RESULTS: During spatial learning, fast gamma (100 to 150 Hz) oscillations synchronized MEC and dentate gyrus and entrained predominantly granule cells. During object learning, slow gamma (30 to 50 Hz) oscillations synchronized LEC and dentate gyrus and preferentially recruited mossy cells and CA3 pyramidal neurons, suggesting task-specific routing of MEC and LEC messages in the form of gamma-cycle-spike packets of selected cell types. The low- and high-frequency gamma sub-bands were dominant in the outer and middle third of the dentate molecular layer, respectively, and their amplitude maxima were locked to different phases of theta oscillation. Gamma frequency optogenenetic perturbation of MEC and LEC led to learning impairments in a spatial and object learning task, respectively. In the same animals, the dentate layer–specific low- and high-frequency gamma sub-bands and spike-gamma LFP coupling were selectively reduced, coupled with deterioration of spatial and object-related parameters of dentate neurons. CONCLUSION: These findings demonstrate that distinct gamma-frequency-specific communication between MEC and LEC and the hippocampal cell assemblies are critical for routing task-relevant information, and our selective gamma-band perturbation experiments suggest that they support specific aspects of learning. We hypothesize that sending neuronal messages by segregated gamma-frequency carriers allows a target “reader” area to disambiguate convergent inputs. In general, these results demonstrate that specific projected gamma patterns dynamically engage functionally related cell assemblies across brain regions in a task-specific manner.post-print2234 K

Observations of the relationship between sprite morphology and in-cloud lightning processes

[1] During a thunderstorm on 23 July 2003, 15 sprites were captured by a LLTV camera mounted at the observatory on Pic du Midi in the French Pyrénées. Simultaneous observations of cloud-to-ground (CG) and intracloud (IC) lightning activity from two independent lightning detection systems and a broadband ELF/VLF receiver allow a detailed study of the relationship between electrical activity in a thunderstorm and the sprites generated in the mesosphere above. Results suggest that positive CG and IC lightning differ for the two types of sprites most frequently observed, the carrot- and column-shaped sprites. Column sprites occur after a short delay (<30 ms) from the causative +CG and are associated with little VHF activity, suggesting no direct IC action on the charge transfer process. On the other hand, carrot sprites are delayed up to about 200 ms relative to their causative +CG stroke and are accompanied by a burst of VHF activity starting 25–75 ms before the CG stroke. While column sprites associate with short-lasting (less than 30 ms) ELF/VLF sferics, carrot sprites associate with bursts of sferics initiating at the time of the causative +CG discharge and persisting for 50 to 250 ms, indicating extensive in-cloud activity. One carrot event was found to be preceded by vigorous IC activity and a strong, long-lived cluster of ELF/VLF sferics but lacking a +CG. The observations of ELF/VLF sferic clusters associated with lightning and sprites form the basis for a discussion of the reliability of lightning detection systems based on VHF interferometry.Peer ReviewedPostprint (published version

Microdosing psychedelics: More questions than answers? An overview and suggestions for future research

Background: In the past few years, the issue of \u2018microdosing\u2019 psychedelics has been openly discussed in the public arena where claims have been made about their positive effect on mood state and cognitive processes such as concentration. However, there are very few scientific studies that have specifically addressed this issue, and there is no agreed scientific consensus on what microdosing is. Aim: This critique paper is designed to address questions that need to be answered by future scientific studies and to offer guidelines for these studies. Approach: Owing to its proximity for a possible approval in clinical use and short-lasting pharmacokinetics, our focus is predominantly on psilocybin. Psilocybin is allegedly, next to lysergic acid diethylamide (LSD), one of the two most frequently used psychedelics to microdose. Where relevant and available, data for other psychedelic drugs are also mentioned. Conclusion: It is concluded that while most anecdotal reports focus on the positive experiences with microdosing, future research should also focus on potential risks of (multiple) administrations of a psychedelic in low doses. To that end, (pre)clinical studies including biological (e.g. heart rate, receptor turnover and occupancy) as well as cognitive (e.g. memory, attention) parameters have to be conducted and will shed light on the potential negative consequences microdosing could have

Relativistic electron beams above thunderclouds

Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency &amp;sim;40–400 kHz which they radiate. The electron beams occur &amp;sim;2–9 ms after positive cloud-to-ground lightning discharges at heights between &amp;sim;22–72 km above thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of &amp;sim;7 MeV to transport a total charge of &amp;sim;−10 mC upwards. The impulsive current &amp;sim;3 &amp;times; 10&lt;sup&gt;&amp;minus;3&lt;/sup&gt; Am&lt;sup&gt;−2&lt;/sup&gt; associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit